The recommended usage pattern of the container classes is the same as
for normal standard containers.

ptr_vector, ptr_list and ptr_deque offer the programmer different
complexity tradeoffs and should be used accordingly. ptr_vector is the
type of sequence that should be used by default. ptr_list should be used
when there are frequent insertions and deletions from the middle of the
sequence and if the container is fairly large (eg. more than 100
elements). ptr_deque is the data structure of choice when most insertions
and deletions take place at the beginning or at the end of the sequence.
The special container ptr_array may be used when the size of the container is invariant
and known at compile time.

An associative container supports unique keys if it may contain at most
one element for each key. Otherwise, it supports equivalent keys.
ptr_set and ptr_map support unique keys.
ptr_multiset and ptr_multimap
support equivalent keys.

Idiomatic Object-Oriented Programming in C++ looks a bit different from
the way it is done in other languages. This is partly because C++
has both value and reference semantics, and partly because C++ is more flexible
than other languages. Below is a list of recommendations that you are
encouraged to follow:

By default the pointer containers do not allow you to store null-pointer in them.
As you might know, this behavior can be changed explicitly with the use
of boost::nullable.

The primary reason to avoid null-pointers
is that you have to check for null-pointers every time the container is
used. This extra checking is easy to forget, and it is somewhat contradictory to
the spirit of OO where you replace special cases with dynamic dispatch.

Often, however, you need to place some special object in the container because you
do not have enough information to construct a full object. In that case
you might be able to use the Null Object pattern which simply dictates that
you implement virtual functions from the abstract base-class
as empty functions or with dummy return values. This means that
your OO-code still does not need to worry about null-pointers.